I have an affinity for hybrids of technology and nature, whether in art or engineering. There was the Coniferous Clock made of cedar, fresh and green in spring, brown and withered in winter, that told a simple tale of a year’s passing.
Here’s a new take on using plants in a sleek design: The CityTree, made by Green City Solutions. CityTree is an urban air filter that uses moss to remove pollutants from city air.

CityTree.
Photo: Via CNN
In a cool trick of using densely packed moss that has more leaf surface area than other plants, the self-contained, mobile units are solar-powered, self-watering and are monitored via sophisticated sensors. They are estimated to remove the same amount of pollutants from city air as up to 275 trees. This can, according to the inventors, add up to the annual removal of 240 metric tons of CO2 per unit.
Like the super neat SmartFlower Solar installations of blossom-shaped solar panels that follow the arc of the sun across the sky – one is at a supermarket just down the road from our house – this is a great concept that has its price. In the case of CityTree, each unit is currently priced at around $25,000. The company states that the units are made from a high proportion of recyclable materials and have a long life, but how does that really break down in terms of resources, disposal, and maintenance over the long term?

CityTree with optional bench.
Image: Green City Solutions
Still, I like it. Even if achieving equivalent results doesn’t always mean the methods were equivalent. Six of one isn’t always the same as half a dozen. After all, plant a hundred trees or cover a hundred house walls in ivy, and you’ll be filtering city air for decades with very little overhead. But for that, you need the soil, the water and the will.
It’s a sign of our poor urban planning that we even need to talk about CityTree, but I have a feeling we might just be seeing more of them. The makers boast that CityTree has the services of a whole forest on the surface of 3.5 sq. meters (37 sq. feet).
It’s an intriguing and creative solution. They’re nice to look at, and I bet they smell almost like a forest.

Oakwood forest, Scotland.
Photo: Forestry Commission Scotland